JP5838753B2 - Hydrostatic gas bearing spindle and electrostatic coating apparatus having the same - Google Patents

Description

  The present invention includes, for example, a coating apparatus and the like, and a static pressure gas bearing spindle that rotatably supports a rotating shaft in a non-contact state by a static pressure gas bearing, and an electrostatic coating apparatus including the static pressure gas bearing spindle About.

Conventionally, as a hydrostatic gas bearing spindle which is provided in a coating apparatus and supports a rotating shaft in a non-contact state by a hydrostatic gas bearing through compressed air or the like, the hydrostatic gas bearing spindle is described in Patent Document 1, for example. There is something.
The hydrostatic gas bearing spindle described in Patent Document 1 has a supply path for supplying gas (compressed air) to the hydrostatic gas bearing, and has a small gap (bearing gap) from the outer diameter surface of the rotating shaft. Then, a series of polygonal air supply passages are formed in the housing to communicate in the circumferential direction a plurality of throttle holes opened on the opposing surfaces (bearing surfaces) and a plurality of throttle holes arranged in the same cross section. Yes. Here, the transverse section is a section viewed from the radial direction of the rotating shaft.

  In the hydrostatic gas bearing spindle described in Patent Document 1, compressed air is allowed to flow from a plurality of throttle holes into the bearing gap so that the rotary shaft is supported in a non-contact manner on the bearing surface of the housing. That is, in the static pressure gas bearing spindle described in Patent Document 1, in order to circulate the compressed air supplied to the static pressure gas bearing in the circumferential direction of the rotating shaft, a gas supply path to the static pressure gas bearing Is formed from a throttle hole and a polygonal air supply passage.

However, since the gas (turbine air) used to rotate the rotating shaft needs to have a larger flow rate per unit time than the gas supplied to the static pressure gas bearing, the turbine air supply path is It is necessary to make the passage larger in cross-sectional area than the polygonal air supply passage.
As the static pressure gas bearing spindle having a configuration in which the supply path of the turbine air is a passage having a larger cross-sectional area than the above-described polygonal supply passage, there is a structure shown in FIGS. 5 and 6, for example. FIG. 5 is a diagram showing a configuration of a conventional static pressure gas bearing spindle, and is a diagram of the static pressure gas bearing spindle as viewed from the axial direction of the rotary shaft. 6 is a cross-sectional view taken along line VI-VI in FIG.

As shown in FIGS. 5 and 6, the static pressure gas bearing spindle 1 includes a housing 2, a rotary shaft 4, a static pressure gas bearing 6, and a turbine unit 10 for rotating the rotary shaft 4. .
The housing 2 is formed in a cylindrical shape and has an internal space penetrating in the axial direction.
The rotating shaft 4 is inserted into the housing 2, and a turbine blade 12 is attached to one end side (the right side in FIG. 6). The turbine section 10 is formed in a disc shape, Is arranged. Further, the outer surface of the turbine unit 10 has turbine blades 12 protruding from the outer surface. Here, in the turbine unit 10, the outer surface from which the turbine blade 12 protrudes is the surface opposite to the surface attached to the rotating shaft 4 (the right surface in FIG. 6).

The static pressure gas bearing 6 is formed of an axial bearing 14 and a radial bearing 16.
The axial bearing 14 is opposed to the surface of the turbine section 10 where the turbine blades 12 do not protrude (the left surface in FIG. 6) in the housing 2, and gas (bearing air) supplied from outside is received. In use, the turbine unit 10 is rotatably supported in the housing 2 in a non-contact state.
The radial bearing 16 is opposed to the outer diameter surface of the rotating shaft 4 in the housing 2, and the rotating shaft 4 is not contacted in the housing 2 using gas (bearing air) supplied from the outside. It is supported so that it can rotate.

Further, in the housing 2, a turbine air ejection nozzle portion 22 is formed for ejecting gas toward the turbine blade 12 so that the rotation shaft 4 rotates in the circumferential direction. Moreover, the housing 2 is a concave groove formed along the entire circumferential direction (entire circumference) of the turbine section 10 on the surface side close to the turbine air ejection nozzle section 22 of both end faces in the axial direction of the housing 2. 24.
An opening 28a communicating with the concave groove 24 is formed in a surface near both ends of the housing 2 in the axial direction close to the turbine air ejection nozzle portion 22, and the opening 28a is formed in the concave groove 24. One end of a communication passage 28 for supplying turbine air that communicates with the nozzle portion 22 for ejecting turbine air is formed.

That is, the turbine air ejection nozzle portion 22, the concave groove 24, and the turbine air supply communication passage 28 form a turbine air supply path.
Here, as described above, the supply path of the turbine air needs to be a passage having a large cross-sectional area. For this reason, the concave groove 24 is arranged on the outer peripheral side (the outer peripheral side of the turbine unit 10) with respect to the turbine blade 12 in order to ensure a cross-sectional area, and when viewed from the radial direction of the rotating shaft 4, They are formed at overlapping positions (see FIG. 6). That is, the concave groove 24 is formed in the outermost diameter portion of the housing 2.

JP-A-8-326753

In the above-described conventional static pressure gas bearing spindle, the concave groove forming the turbine air supply path is arranged on the outer peripheral side of the turbine blade, and at a position overlapping the turbine blade as viewed from the radial direction of the rotating shaft. Forming.
For this reason, since the position of the concave groove is a position that overlaps with the turbine blade when viewed from the radial direction of the rotating shaft, the bearing air supply opening that forms a gas supply path to the static pressure gas bearing in the concave groove Is difficult to form.
As a result, a portion for forming a bearing air supply opening for forming a gas supply path to the static pressure gas bearing is secured on the surface of the housing opposite to the surface from which one end of the rotating shaft projects. For this purpose, it is necessary to enlarge a portion of the housing where the concave groove is not formed, that is, a portion on the inner diameter side of the concave groove.

However, when the portion of the housing on the inner diameter side with respect to the concave groove is enlarged, the outer diameter of the housing is increased, which causes a problem that it is difficult to reduce the weight and size of the hydrostatic gas bearing spindle.
The present invention has been made paying attention to the above-mentioned problems, and provides a hydrostatic gas bearing spindle capable of reducing the outer diameter of a housing and reducing the weight and size. Is an issue.

In order to solve the above problems, the invention described in claim 1 is a housing,
A rotating shaft rotatably supported by a hydrostatic gas bearing in the housing;
A disc-shaped turbine portion attached to one end of the rotating shaft in the housing and having turbine blades;
A turbine air jet nozzle part formed in the housing and for jetting gas toward the turbine blades,
The housing does not overlap the turbine portion when viewed from the radial direction and the axial direction of the rotary shaft on the first housing end surface side which is the end surface on the side close to the turbine air ejection nozzle portion of both end surfaces in the axial direction. Turbine air that communicates the concave groove formed at the position along the circumferential direction of the rotating shaft and having a discontinuous portion in the circumferential direction, and the nozzle section for ejecting the turbine air and the concave groove. A supply communication passage, and a non-concave groove portion which is the discontinuous portion ,
The gas is directed toward the back surface of the surface of the turbine blade where the nozzle for jetting the gas blows out of the portion of the first housing end surface overlapping the non-concave groove portion as viewed from the axial direction of the rotating shaft. And a brake air supply nozzle for supplying gas to the static pressure gas bearing, and a brake air supply nozzle that communicates via a brake air supply nozzle and a brake air supply communication passage. At least one of the communicating air supply openings is formed .

According to the present invention, the concave groove that communicates with the turbine air ejection nozzle portion by the turbine air supply communication passage is formed in the housing at a position that does not overlap the turbine portion when viewed from the radial direction and the axial direction of the rotating shaft. doing.
For this reason, the position of the concave groove when viewed from the radial direction of the rotating shaft is a position that does not overlap with the turbine part, and the position of the housing that overlaps with the concave groove when viewed from the radial direction of the rotating shaft is transferred to the hydrostatic gas bearing. It is possible to form an opening that forms a gas supply path.
According to the present invention, the concave groove extends along the circumferential direction of the rotating shaft and has a discontinuous portion in the circumferential direction of the rotating shaft, and the housing is formed by the discontinuous portion of the concave groove. It has a certain non-concave groove portion. In addition to this, in the portion of the first housing end surface that overlaps the non-concave groove portion when viewed from the axial direction of the rotating shaft, the gas is directed toward the back surface of the surface of the turbine blade where the turbine air ejection nozzle portion ejects gas. Communicating with a brake air jet nozzle for jetting, a brake air supply opening communicating with the brake air supply communication passage, and a bearing air supply communication passage for supplying gas to the static pressure gas bearing At least one of the bearing air supply openings is formed.
Therefore, at least one of the brake air supply opening and the bearing air supply opening can be formed at a position overlapping the concave groove when viewed from the radial direction of the rotating shaft.

Next, among the present inventions, the invention described in claim 2 is an invention dependent on claim 1 , and is a radial direction of the wall surface on the outer peripheral side of the concave groove and the rotating shaft of the non-concave groove portion. And one or a plurality of voids are formed in the opposing portions.
According to the present invention, among the non-concave groove portions, one or a plurality of gaps are formed in the portion facing the outer peripheral wall surface of the concave groove in the radial direction of the rotating shaft.
For this reason, since the pressure (atmospheric pressure) in the radial direction of the rotating shaft is applied to the non-concave groove portion by the gas supplied to the gap portion as in the concave groove, when the gas is supplied to the concave groove and the gap portion, The pressure in the radial direction of the rotating shaft is applied to the inner peripheral wall surface of the concave groove and the non-concave groove portion in the circumferential direction of the rotating shaft.

Next, of the present invention, the invention described in claim 3 is an invention dependent on claim 1 or claim 2 , wherein the housing includes a first housing part in which the concave groove is formed, A second housing part that is attached to a surface of the first housing part opposite to the first housing end face;
A housing fastening member for attaching the second housing part to the first housing part is arranged at a position overlapping the concave groove when viewed from the axial direction of the rotating shaft.

According to the present invention, the housing includes a first housing portion and a second housing portion, and the housing fastening member for attaching the second housing portion to the first housing portion is a concave groove when viewed from the axial direction of the rotary shaft. It is arranged at the position that overlaps.
For this reason, it becomes possible to attach a 2nd housing part to a 1st housing part, without arrange | positioning a housing fastening member in the part of an inner diameter side rather than a concave groove among housings.

Next, among the present inventions, the invention described in claim 4 is provided with the static pressure gas bearing spindle described in any one of claims 1 to 3. It is.
According to the present invention, the configuration of the electrostatic coating apparatus includes a static pressure gas bearing spindle that is reduced in weight and size.
For this reason, the electrostatic coating apparatus can be reduced in weight and size.

According to the present invention, the position of the concave groove when viewed from the radial direction of the rotating shaft is a position that does not overlap with the turbine portion, and the static pressure gas is positioned at the position of the housing that overlaps with the concave groove when viewed from the radial direction of the rotating shaft. An opening that forms a gas supply path to the bearing can be formed.
For this reason, the gas supply path to the static pressure gas bearing is provided on the surface of the housing opposite to the surface on which the one end side of the rotating shaft protrudes without enlarging the inner diameter side portion of the housing. It is possible to secure a portion for forming the opening to be formed. As a result, the outer diameter of the housing can be reduced, and a hydrostatic gas bearing spindle that can be reduced in weight and size can be provided.

It is sectional drawing which shows the structure of the static pressure gas bearing spindle of 1st embodiment of this invention. It is the II-II sectional view taken on the line of FIG. FIG. 3 is an enlarged view showing a range surrounded by a circle III in FIG. 2 and its periphery. It is an enlarged view which shows the range enclosed with the circle IV in FIG. 1, and its periphery. It is a figure which shows the structure of the static pressure gas bearing spindle of a prior art example, and is the figure which looked at the static pressure gas bearing spindle from the axial direction of the rotating shaft. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5.

(First embodiment)
Hereinafter, a first embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the drawings.
(Constitution)
First, the configuration of the static pressure gas bearing spindle will be described with reference to FIGS.
FIG. 1 is a cross-sectional view showing a configuration of a static pressure gas bearing spindle 1 of the present embodiment. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is an enlarged view showing a range surrounded by a circle III in FIG. 2 and its periphery. FIG. 4 is an enlarged view showing a range surrounded by a circle IV in FIG. 1 and its periphery. 1 to 4, the same configuration as that of the above-described conventional static pressure gas bearing spindle 1 is shown with the same reference numerals as in FIGS. 5 and 6.

As shown in FIGS. 1 to 4, the static pressure gas bearing spindle 1 includes a housing 2, a rotating shaft 4, and a static pressure gas bearing 6.
In this embodiment, the case where the static pressure gas bearing spindle 1 is provided in the electrostatic coating apparatus will be described as an example. That is, the static pressure gas bearing spindle 1 of this embodiment is used in an electrostatic coating apparatus.
The housing 2 is formed in a cylindrical shape, and has an internal space penetrating in the axial direction (in the drawing, indicated as “axial direction” by a bidirectional arrow). The detailed configuration of the housing 2 will be described later.

The rotating shaft 4 is formed in a cylindrical shape and is rotatably supported in the housing 2 by a static pressure gas bearing 6.
A coating jig 8 is attached to a portion of the rotating shaft 4 protruding from the housing 2. The coating jig 8 is supplied with paint from a tank not shown.
Further, a turbine blade 10 is attached to one end side (right side in FIG. 2) of the rotating shaft 4. The turbine unit 10 is formed in a disc shape and is disposed in the housing 2.

The turbine unit 10 has a plurality of turbine blades 12 protruding from the outer surface. Here, in the turbine unit 10, the outer surface from which the turbine blade 12 protrudes is a surface opposite to the surface attached to the rotating shaft 4 (the right surface in FIG. 2).
In this embodiment, as an example, a case where the turbine unit 10 and the turbine blade 12 are integrated is described. However, the present invention is not limited to this, and the turbine unit 10 and the turbine blade 12 may be separated. Good.

Each of the plurality of turbine blades 12 is a plate-like member formed such that a cross section in the height direction has an arc shape. On the outer surface of the turbine unit 10, the circumferential direction of the turbine unit 10 (both in the drawing) Are indicated by a directional arrow ("circumferential direction").
Here, the height direction of the turbine blade 12 is parallel to the axial direction of the rotating shaft 4. Further, the plurality of turbine blades 12 are arranged over the entire circumference along the circumferential direction of the turbine unit 10 with the same arc direction.

The static pressure gas bearing 6 is formed of an axial bearing 14 and a radial bearing 16, and supports the rotating shaft 4 and the turbine unit 10 to be rotatable in the housing 2.
The axial bearing 14 is opposed to the surface of the turbine unit 10 where the turbine blades 12 are not formed (the left surface in FIG. 2) in the housing 2, and the gas supplied from the outside (bearing air). Is ejected to the turbine section 10 to rotatably support the rotating shaft 4 in a non-contact state.

Moreover, the axial bearing 14 is provided with a magnet (not shown), and the repulsive force between the axial bearing 14 and the turbine unit 10 generated by the bearing air jetted to the turbine unit 10 and the attraction force generated by the magnets. By adjusting the balance, the gap between the axial bearing 14 and the turbine section 10 (the gap in the direction indicated as “axial direction” in FIG. 2) is maintained at a preset appropriate value.
The radial bearing 16 is opposed to the outer diameter surface of the rotating shaft 4 in the housing 2 and supports the rotating shaft 4 in a non-contact state using gas (bearing air) supplied from the outside. To do.

Hereinafter, a detailed configuration of the housing 2 will be described.
The housing 2 includes a first housing part 18 and a second housing part 20.
The first housing portion 18 has a first housing end surface 2a (a right-side surface in FIG. 2), which is a surface closer to a turbine air ejection nozzle portion 22 to be described later, of both end surfaces in the axial direction of the housing 2. Have.

The first housing portion 18 includes a concave groove 24, a first bearing air supply communication passage 26, a turbine air supply communication passage 28, a turbine air supply communication passage 42, and a brake air supply communication passage. 44.
The concave groove 24 is formed on the first housing end face 2 a side in the first housing portion 18. That is, the concave groove 24 is formed in the first housing portion 18 on the first housing end surface 2a side, which is a surface closer to a turbine air ejection nozzle portion 22 to be described later, of both end surfaces of the housing 2 in the axial direction. Has been.

The concave groove 24 is formed at a position that does not overlap the turbine section 10 when viewed from the radial direction of the rotating shaft 4 (in the drawing, indicated as “radial direction” by a bidirectional arrow) and the axial direction.
The concave groove 24 extends along the circumferential direction of the rotating shaft 4 and is formed to have a discontinuous portion in the circumferential direction of the rotating shaft 4.
Thereby, the 1st housing part 18 has the non-concave groove part 30 which is the part in which the concave groove 24 is discontinuous in the 1st housing end surface 2a side among the inside. That is, the housing 2 has a non-concave groove portion 30 on the first housing end face 2a side in the inside thereof.

Further, when viewed from the axial direction of the rotary shaft 4, a bearing air supply opening 32 communicating with the first bearing air supply communication passage 26 is formed in a portion of the first housing end surface 2 a overlapping the non-concave groove portion 30. Is formed.
The first bearing air supply communication passage 26 is formed inside the first housing portion 18.
Further, one end of the first bearing air supply communication passage 26 is formed with a bearing air supply opening 32.

On the other hand, the other end of the first bearing air supply communication passage 26 is open to a surface of the first housing portion 18 opposite to the first housing end surface 2a (the left surface in FIG. 2).
Further, in the non-concave groove portion 30, a gap 34 is formed in a portion facing the outer peripheral wall surface of the concave groove 24 in the radial direction of the rotary shaft 4 when viewed from the axial direction of the rotary shaft 4. .
In the present embodiment, as an example, one gap portion 34 is formed over the entire circumferential direction of the rotating shaft 4, and the non-concave groove portion 30 is rotated by the one gap portion 34. The case where the concave grooves 24 facing in the circumferential direction of the shaft 4 communicate with each other will be described.
The turbine air supply communication passage 28 is formed inside the first housing portion 18, and communicates the turbine air ejection nozzle portion 22 and the concave groove 24.
Specifically, one end of the turbine air supply communication passage 28 is opened at the bottom surface of the concave groove 24 (indicated by reference numeral “28a” in the drawing).

Further, an opening (indicated by reference numeral “28b” in the drawing) that communicates with the turbine air ejection nozzle portion 22 is opened on the inner peripheral surface of the turbine air supply communication passage 28.
In the present embodiment, as an example, a case in which six turbine air supply passages 28 are formed will be described. The six turbine air supply communication passages 28 are evenly arranged along the circumferential direction of the rotating shaft 4.

Further, the turbine air supply communication passage 28 is formed so that its inner diameter is equal to or larger than the inner diameter of the turbine air ejection nozzle portion 22. Further, the turbine air supply communication passage 28 and the turbine air ejection nozzle portion 22 are orthogonal to each other inside the first housing portion 18.
The turbine air supply communication passage 42 is formed inside the first housing portion 18.

Further, one end of the turbine air supply communication path 42 is open to the first housing end surface 2 a, and the other end of the turbine air supply communication path 42 is in communication with the concave groove 24.
In the drawings and the following description, an opening which is one end of the turbine air supply communication passage 42 and is open to the first housing end surface 2a is referred to as a turbine air supply opening 42a.
Therefore, the turbine air supply communication passage 42 allows the external space of the first housing portion 18 and the concave groove 24 to communicate with each other.

The turbine air supply opening 42 a communicates with the turbine air supply communication path 28 via the concave groove 24.
The turbine air ejection nozzle portion 22 is formed on the inner diameter surface of the first housing portion 18 and is formed so as to eject gas toward the turbine blade 12 so that the rotation shaft 4 rotates in the circumferential direction. Yes. That is, the first housing portion 18 includes a turbine air ejection nozzle portion 22.
In the present embodiment, six turbine air supply passages 28 are formed. For this reason, in the present embodiment, a case is described in which six turbine air ejection nozzle portions 22 are formed and are equally disposed along the circumferential direction of the rotary shaft 4, similarly to the turbine air supply communication passage 28. To do.

Specifically, one end of the turbine air ejection nozzle portion 22 is opened in a shape that ejects gas in a direction facing the concave surface (surface having a small arc) of the turbine blade 12 on the inner diameter surface of the first housing portion 18. doing.
The brake air supply communication passage 44 is formed inside the first housing portion 18, similarly to the turbine air supply communication passage 42.

Further, one end of the brake air supply communication path 44 is opened in a portion of the first housing end surface 2a that overlaps the non-concave groove portion 30 when viewed from the axial direction of the rotary shaft 4, and the brake air supply communication path The other end of 44 communicates with the brake air ejection nozzle portion 46.
In the drawings and the following description, it is one end of the brake air supply communication passage 44 and opens to a portion of the first housing end surface 2a that overlaps the non-concave groove portion 30 when viewed from the axial direction of the rotary shaft 4. This opening is indicated as a brake air supply opening 44a.
Therefore, the brake air supply communication passage 44 allows the external space of the first housing portion 18 and the brake air ejection nozzle portion 46 to communicate with each other via the brake air supply opening 44a.

The brake air ejection nozzle portion 46 is formed on the inner diameter surface of the first housing portion 18, and ejects gas toward the back surface of the turbine blade 12 where the turbine air ejection nozzle portion 22 ejects gas. It is formed to do.
As a result, the brake air ejection nozzle portion 46 gas toward the turbine blade 12 so as to suppress the rotation of the rotating shaft 4 rotating in the circumferential direction by the gas ejected from the turbine air ejection nozzle portion 22. It is formed to erupt.
Specifically, one end of the brake air ejection nozzle portion 46 allows gas to flow in a direction opposite to a surface (a surface having a large arc) opposite to the concave surface of the turbine blade 12 on the inner diameter surface of the first housing portion 18. It opens in a shape that erupts.

The second housing part 20 is attached to a surface of the first housing part 18 opposite to the first housing end face 2a using a housing fastening member 36.
The housing fastening member 36 is formed using, for example, a bolt, passes through the second housing part 20, and the second housing is connected to the first housing part 18 in a state where the distal end side is screwed into the first housing part 18. Part 20 is attached.

The housing fastening member 36 is disposed at a position overlapping the concave groove 24 when viewed from the axial direction of the rotating shaft 4.
In addition, the second housing portion 20 has a second air supply passage for supplying gas from the outside to the axial bearing 14 and the radial bearing 16 via the bearing air supply opening 32 and the first bearing air supply communication passage 26. A two-bearing air supply communication path 38 is formed.
In addition, one end of the second bearing air supply communication path 38 is open to the surface (the right surface in FIG. 2) of the second housing portion 20 that faces the first housing portion 18. The bearing air supply communication path 26 communicates with the other end.

On the other hand, the other end side of the second bearing air supply communication passage 38 is branched into a plurality of branches, and these branch destinations communicate with the axial bearing 14 and the radial bearing 16.
As described above, the first bearing air supply communication passage 26 and the second bearing air supply communication passage 38 form a bearing air supply communication passage for supplying gas to the axial bearing 14 and the radial bearing 16 from the outside. Yes.

Further, a bearing air exhaust path 40 for exhausting the gas jetted to the axial bearing 14 and the radial bearing 16 to the outside of the housing 2 is formed inside the second housing portion 20.
One end of the bearing air exhaust passage 40 communicates with the rotary shaft 4 and the space between the turbine part 10 and the first housing part 18.
On the other hand, the other end of the bearing air exhaust path 40 is open to a surface (the left surface in FIG. 2) of the second housing portion 20 opposite to the surface facing the first housing portion 18.

(Operation / Action)
Next, the operation and action of the static pressure gas bearing spindle 1 will be described with reference to FIGS.
A compressor capable of supplying gas (compressed air) to the bearing air supply opening 32 and the turbine air supply opening 42a with respect to the first housing end surface 2a of the first housing portion 18 when the static pressure gas bearing spindle 1 is used. Connect etc.
In addition, when the static pressure gas bearing spindle 1 is used, a compressor or the like capable of supplying gas to the brake air supply opening 44a is connected to the first housing end surface 2a of the first housing portion 18.

Then, gas is supplied from these connected compressors and the like to the bearing air supply opening 32 and the turbine air supply opening 42a to operate the static pressure gas bearing spindle 1.
The gas supplied to the bearing air supply opening 32 is supplied to the axial bearing 14 and the radial bearing 16 via the first bearing air supply communication passage 26 and the second bearing air supply communication passage 38.
Thereby, the axial bearing 14 and the radial bearing 16 support the rotating shaft 4 rotatably in a non-contact state. The gas supplied to the axial bearing 14 is exhausted from a path that passes through the periphery of the turbine unit 10 and communicates with the outside of the housing 2 and a path that communicates with the outside of the housing 2 via the bearing air exhaust path 40.

Further, the gas supplied to the radial bearing 16 is ejected to the outer diameter surface of the rotating shaft 4. Thereby, the radial bearing 16 supports the rotating shaft 4 so that rotation is possible in a non-contact state. Then, the gas supplied to the radial bearing 16 and ejected to the outer diameter surface of the rotary shaft 4 passes to the outside of the housing 2 as it is from the radial bearing 16 and to the outside of the housing 2 through the bearing air exhaust path 40. Exhausted from the route that leads to it.
The gas supplied to the turbine air supply opening 42 a is supplied to the concave groove 24, moves from the concave groove 24 to the turbine air supply communication passage 28, flows into the turbine air ejection nozzle portion 22, and It is ejected toward the blade 12.

The gas ejected toward the turbine blade 12 rotates the rotating shaft 4 in the circumferential direction.
Then, as the rotary shaft 4 rotates, the coating jig 8 also rotates in the circumferential direction of the rotary shaft 4.
Here, in this embodiment, the static pressure gas bearing spindle 1 is used for the electrostatic coating apparatus.
Therefore, in a state where the gas is supplied to the bearing air supply opening 32, the gas is supplied from the turbine air supply opening 42a to the concave groove 24 and the gap 34, and then from a tank (not shown) to a tube (not shown). The coating material is supplied to the coating jig 8 via In addition, the coating jig 8 is charged negatively. Thereby, the coating material supplied to the coating jig 8 is centrifuged by the rotation from the coating jig 8 that rotates in the circumferential direction of the rotating shaft 4 (high-speed rotation) as the rotating shaft 4 rotates (high-speed rotation). It becomes fine particles by force.

The finely divided paint moves toward the surface to be coated (such as the surface of the material) that is grounded by electrostatic attraction, and adheres to the surface to be coated.
In the present embodiment, when the static pressure gas bearing spindle 1 is used, gas is supplied from the turbine air supply opening 42 a to the gap 34 together with the concave groove 24.
For this reason, when gas is supplied to the concave groove 24 and the gap portion 34, both the portion of the non-concave groove portion 30 in which the gap portion 34 is formed and the inner peripheral wall surface of the concave groove 24 both have the rotation shaft 4. The pressure in the radial direction of the rotating shaft 4 is applied over the circumferential direction.
Thereby, when the static pressure gas bearing spindle 1 is used, the pressure in the radial direction of the rotating shaft 4 is uniformly applied to the first housing portion 18 in the circumferential direction of the rotating shaft 4.

When the static pressure gas bearing spindle 1 in operation is stopped, for example, when the coating on the surface to be coated is completed, the brake air is supplied from the compressor or the like connected to the first housing end surface 2a of the first housing portion 18. Gas is supplied to the supply opening 44a.
The gas supplied to the brake air supply opening 44a moves to the brake air supply communication passage 44, flows into the brake air ejection nozzle portion 46, and toward the surface opposite to the concave surface of the turbine blade 12. Is ejected. Thereby, the gas spouted toward the surface opposite to the concave surface of the turbine blade 12 suppresses the rotation of the rotating shaft 4 rotating in the circumferential direction. For this reason, the rotation of the coating jig 8 is also suppressed, and the operating static pressure gas bearing spindle 1 stops.

(Effects of the first embodiment)
The effects of this embodiment are listed below.
(1) In the static pressure gas bearing spindle 1 of the present embodiment, the concave groove 24 communicating with the turbine air ejection nozzle portion 22 by the turbine air supply communication passage 28 is viewed from the radial direction and the axial direction of the rotary shaft 4. , At a position that does not overlap with the turbine section 10.
For this reason, the position of the concave groove 24 seen from the radial direction of the rotating shaft 4 is a position that does not overlap the turbine section 10. Thus, a bearing air supply opening 32 that forms a gas supply path to the static pressure gas bearing 6 is formed in the housing 2 at a position overlapping the concave groove 24 when viewed from the radial direction of the rotary shaft 4. Is possible.

As a result, without expanding the portion of the housing 2 on the inner diameter side of the concave groove 24, the surface of the housing 2 opposite to the surface from which one end side of the rotating shaft 4 projects is connected to the static pressure gas bearing 6. It is possible to secure a portion for forming the bearing air supply opening 32 that forms the gas supply path.
Thereby, the outer diameter dimension of the housing 2 can be reduced, and the static pressure gas bearing spindle 1 can be reduced in weight and size.

(2) In the static pressure gas bearing spindle 1 of the present embodiment, the concave groove 24 is formed to extend along the circumferential direction of the rotating shaft 4 and to have a discontinuous portion in the circumferential direction of the rotating shaft 4. Yes. Furthermore, the housing 2 has the non-concave groove part 30 which is said discontinuous part. In addition to this, as viewed from the axial direction of the rotating shaft 4, for supplying brake air for supplying gas to the nozzle portion 46 for ejecting the brake air to a portion of the first housing end surface 2 a that overlaps the non-concave groove portion 30. The opening 44a and the bearing air supply opening 32 for supplying gas to the static pressure gas bearing 6 are formed.

Therefore, the brake air supply opening 44a that forms a gas supply path to the brake air ejection nozzle 46 and the bearing air supply opening 32 that forms a gas supply path to the static pressure gas bearing 6 are provided. When viewed from the radial direction of the rotating shaft 4, it can be formed at a position overlapping the concave groove 24.
As a result, the brake air supply opening 44a and the bearing air supply opening 32 are not formed in the concave groove 24, and the brake 2 is provided on the surface of the housing 2 opposite to the surface from which one end of the rotary shaft 4 protrudes. It is possible to secure a portion for forming the air supply opening 44a and the bearing air supply opening 32.
(3) In the hydrostatic gas bearing spindle 1 of the present embodiment, one non-concave groove portion 30 has a single gap portion 34 at a portion facing the outer peripheral wall surface of the concave groove 24 in the radial direction of the rotating shaft 4. Is forming.

For this reason, the pressure (atmospheric pressure) in the radial direction of the rotating shaft 4 is applied to the non-concave groove portion 30 by the gas supplied to the gap portion 34 as in the case of the concave groove 24, so that Is supplied to the inner peripheral wall surface of the concave groove 24 and the non-concave groove portion 30 in the radial direction of the rotary shaft 4 over the circumferential direction of the rotary shaft 4.
As a result, the pressure in the radial direction of the rotating shaft 4 applied to the first housing portion 18 can be averaged over the circumferential direction of the rotating shaft 4 when the gas is supplied to the concave groove 24 and the gap portion 34. It becomes possible, and it becomes possible to suppress the deformation of the housing 2 including the first housing portion 18.

(4) In the static pressure gas bearing spindle 1 of the present embodiment, the housing 2 is configured to include the first housing portion 18 and the second housing portion 20, and the second housing portion 20 is attached to the first housing portion 18. The housing fastening member 36 is disposed at a position overlapping the concave groove 24 when viewed from the axial direction of the rotating shaft 4.
For this reason, it is possible to attach the second housing part 20 to the first housing part 18 without disposing the housing fastening member 36 in a portion of the housing 2 on the inner diameter side of the concave groove 24.
As a result, it is possible to reduce the outer diameter of the housing 2 as compared with the case where the housing fastening member 36 is disposed on the inner diameter side of the concave groove 24 when viewed from the axial direction of the rotating shaft 4. The static pressure gas bearing spindle 1 can be reduced in weight and size.

(5) In the present embodiment, the configuration of the electrostatic coating apparatus includes a static pressure gas bearing spindle 1 that is reduced in weight and size.
As a result, the electrostatic coating apparatus can be reduced in weight and size. Further, since the static pressure gas bearing spindle 1 is reduced in weight and size, it is possible to reduce energy consumption (power consumption, etc.) necessary for using the electrostatic coating apparatus.

(Modification)
Hereinafter, modifications of the present embodiment will be listed.
(1) In the static pressure gas bearing spindle 1 of the present embodiment, the brake air supply opening 44a and the portion that overlaps the non-concave groove portion 30 in the first housing end surface 2a when viewed from the axial direction of the rotary shaft 4 and Although the bearing air supply opening 32 is formed, the present invention is not limited to this. That is, when viewed from the axial direction of the rotary shaft 4, the brake air supply opening 44 a and the bearing air supply opening 32 of the first housing end surface 2 a overlap with the non-concave groove portion 30. Only the opening 44a for use may be formed. Further, when viewed from the axial direction of the rotating shaft 4, the bearing air supply of the brake air supply opening 44 a and the bearing air supply opening 32 is formed in a portion of the first housing end surface 2 a overlapping the non-concave groove portion 30. Only the opening 32 for use may be formed.

(2) In the static pressure gas bearing spindle 1 of the present embodiment, the gap portion 34 is formed only at one place over the entire circumferential direction of the rotary shaft 4, but the present invention is not limited to this. For example, a plurality of locations may be formed intermittently along the circumferential direction of the rotating shaft 4. In this case, the concave grooves 24 facing each other in the circumferential direction of the rotating shaft 4 with the non-concave groove portion 30 interposed therebetween are not in communication.
(3) In the static pressure gas bearing spindle 1 of the present embodiment, the housing 2 is configured to include the first housing part 18 and the second housing part 20, but the present invention is not limited to this, and the housing 2 is integrated. You may form with a thing.

(4) In the static pressure gas bearing spindle 1 of the present embodiment, the outer surface of the turbine portion 10 from which the turbine blades 12 protrude is the surface opposite to the surface attached to the rotary shaft 4. It is not limited to. That is, the outer surface of the turbine unit 10 from which the turbine blades 12 protrude may be, for example, the outer diameter surface of the turbine unit 10.
(5) In the present embodiment, the static pressure gas bearing spindle 1 is used in the electrostatic coating apparatus, but the present invention is not limited to this, and the static pressure gas bearing spindle 1 is used for, for example, a dental handpiece. May be.

DESCRIPTION OF SYMBOLS 1 Static pressure gas bearing spindle 2 Housing 2a 1st housing end surface 4 Rotating shaft 6 Static pressure gas bearing 8 Coating jig 10 Turbine part 12 Turbine blade 14 Axial bearing 16 Radial bearing 18 First housing part 20 Second housing part 22 Turbine Nozzle portion for air ejection 24 Concave groove 26 First bearing air supply communication passage 28 Turbine air supply communication passage 28a, 28b Opening portion of turbine air supply communication passage 30 Non-concave groove portion 32 Bearing air supply opening portion 34 Gap Part 36 Housing fastening member 38 Second bearing air supply communication path 40 Bearing air exhaust path 42 Turbine air supply communication path 42a Turbine air supply opening 44 Brake air supply communication path 44a Brake air supply opening 46 Brake Air jet nozzle

Claims (4)

A housing;
A rotating shaft rotatably supported by a hydrostatic gas bearing in the housing;
A disc-shaped turbine portion attached to one end of the rotating shaft in the housing and having turbine blades;
A turbine air jet nozzle part formed in the housing and for jetting gas toward the turbine blades,
The housing does not overlap the turbine portion when viewed from the radial direction and the axial direction of the rotary shaft on the first housing end surface side which is the end surface on the side close to the turbine air ejection nozzle portion of both end surfaces in the axial direction. Turbine air that communicates the concave groove formed at the position along the circumferential direction of the rotating shaft and having a discontinuous portion in the circumferential direction, and the nozzle section for ejecting the turbine air and the concave groove. A supply communication passage, and a non-concave groove portion which is the discontinuous portion ,
The gas is directed toward the back surface of the surface of the turbine blade where the nozzle for jetting the gas blows out of the portion of the first housing end surface overlapping the non-concave groove portion as viewed from the axial direction of the rotating shaft. And a brake air supply nozzle for supplying gas to the static pressure gas bearing, and a brake air supply nozzle that communicates via a brake air supply nozzle and a brake air supply communication passage. A hydrostatic gas bearing spindle, wherein at least one of the communicating bearing air supply openings is formed . Wherein the outer peripheral side wall surface portion facing in the radial direction of the rotary shaft of the concave grooves of the non-recessed groove portions, according to claim 1, characterized in that the formation of the gap portion of one place or a plurality of locations Hydrostatic gas bearing spindle. The housing includes a first housing part in which the concave groove is formed, and a second housing part attached to a surface of the first housing part opposite to the first housing end face,
Claim 1 or claim 2, characterized in that the housing fastening member for mounting said second housing portion to said first housing portion, and when viewed from the axial direction of the rotary shaft is disposed at a position overlapping with the concave groove The hydrostatic gas bearing spindle described in 1. An electrostatic coating apparatus comprising the hydrostatic gas bearing spindle according to any one of claims 1 to 3 .

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